This invention relates to a spinner tool for boreholes, and more particularly to a tool for accurately locating points of fluid entry into producing petroleum wells.
In the operation of boreholes such as petroleum wells and the like, it is sometimes desirable to perform various logging operations. Such logging operations are carried out by lowering a tool into the borehole in such a way as to continuously monitor the positioning of the tool. The tool is provided with transducers responsive to one or more operating parameters of the borehole, such as temperature, fluid flow rate, etc. In this manner there is prepared a record or chart upon which the operating parameters of the borehole as measured by the tool are plotted against the depths of the borehole.
Although prior logging tools have provided much valuable information, they have generally been unsuccessful in identifying the precise location in the well at which fluids are entering the casing of the well. For example, on the assumption that any substantial fluid flow would cause cooling, attempts have been made to utilize temperature measurements to identify points at which fluid is entering the well casing. It has been found, however, that the fluid may flow for a substantial distance along the outside of the casing, and that when this occurs a temperature sensitive well logging tool is incapable of identifying the precise point at which fluid is entering the casing. Various spinner devices have also been utilized heretofore to measure fluid flow, and attempts have been made to utilize such devices to identify the point at which fluid is entering the casing. However, the prior art spinner tools have been responsive to overall fluid flow upwardly in the casing, and for this reason have been less than wholly satisfactory in precisely identifying the point of fluid entry into the well casing.
The present invention comprises a spinner tool for use in boreholes and the like which overcomes the foregoing and other difficulties long since associated with the prior art. In accordance with the broader aspects, a spinner tool includes a rotor mounted for rotation about a normally vertically disposed axis and having a plurality of axially extending rotor blades. The rotor is mounted in a housing having a plurality of axially disposed, angularly extending slots formed therein. The rotor is thus rotated under the action of fluid flowing radially, but is not rotated under the action of fluid flowing axially. In this manner the spinner tool is adapted to provide an output indicative of the precise location at which fluid is entering a borehole.
In accordance with more specific aspects of the invention, the rotor is supported in the housing by means of bearing structure which is effectively self-cleaning. A plurality of permanent magnets are mounted in the upper portion of the rotor for rotation therewith. The magnets function to open and close a switching device, and circuitry is provided in the tool for amplifying and shaping the resulting output signal. This signal is transmitted to the surface where it is recorded by means of conventional recording apparatus to provide a record or chart showing the precise location at which fluid is entering the borehole.